1. Field of the Invention
The present invention relates to a liquid ejection apparatus configured to eject liquid such as ink, a controller for controlling the apparatus, and a nonvolatile storage medium storing a program for controlling the apparatus.
2. Description of the Related Art
An ink-jet printer as one example of a liquid ejection apparatus includes an ink jet head (liquid ejection head) having a multiplicity of ejection openings through which liquid such as ink is ejected to record an image on a recording medium. Here, a viscosity of the liquid in the head may increase by vaporization of water (water content) of the liquid via the ejection openings. This increase in the viscosity of the liquid in the head (especially in the ejection openings) may cause various problems such as clogging of the ejection opening, leading to an ejection failure.
As a technique for preventing the increase in the viscosity of the liquid in the head, there are known: a technique for discharging high-viscosity liquid by preliminary ejection that includes purging (that is an operation for driving a pump so as to apply pressures to the liquid in the head to eject the liquid from all the ejection openings) and flushing (that is an operation for driving actuators of the head on the basis of flushing data (different from image data) to eject the liquid from part or all of the ejection openings); and a technique for humidifying an ejection space facing the ejection openings, in a state in which the ejection space is sealed or capped by the cap. It is noted that water vaporization of the liquid in the ejection openings can be suppressed by the humidification. In addition to this effect, it is possible to consider that even if the viscosity of the liquid in the ejection opening has already increased, water (water content) is supplied to the liquids in the ejection opening by the humidification, making it possible to lower (recover) the viscosity of the liquid in the ejection opening to a value within a proper range.